First of all, I don't know if this damages somehow the built in DirectX 12 installation of Windows 10 but I think it doesn't and don't see the reason how it would for DirectX installers do check if components of the installations need to be updated and don't replace the whole installation. Still, if you somehow damage your Windows 10 installation or hardware by doing this, I am not responsible.
So, I made a clean install of Windows 10 after upgrading to it. After getting all of the drivers and other software installed, I installed Skyrim and restored my mod setup. When I tried to boot the game, it would crash instantly, before the Bethesda logo. This could be fixed by deleting the d3d9.dll binary that is required for ENBs, so it clearly was not a load order issue (as it shouldn't have been as my load order was identical to the load order on Windows 7 installation).
Well, first I tried to install the injector version of the ENB. That got me through the Bethesda logo, but crashed after that.
The fix that worked for me, so I could run the wrapper version of ENB was to install the DirectX End-User Runtimes (June 2010) from Microsofts official website.
There is the link for it. I haven't posted to these forums much, so I am not sure actually if we are allowed to post links, so moderators feel free to edit the post if it is against the rules and apologies for the inconvenience. D:
And if the link is removed, you can find the right page (Microsoft's official website) by googling "DirectX End-User Runtimes (June 2010)", at the time of writing this.
After following the link it gives a download for directx_Jun2010_redist.exe, which asks you for a location to unpack the files. Give it a temporary location, then find the files that were unpacked and run the DXSETUP.exe. This is what actually installs the DirectX 9 components that ENB neets to start without crashing. (Thanks for this clarification to Realfriend)
As this is getting rambly, I hope that I helped at least someone. It took me 8 hours of stressful googling and not finding a solution. Somebody in the ENBseries forums had posted half a year ago that he had had some very similar crashing with a preview build of Windows 10 and had installed DirectX 9.0c to fix this. As the web installer DirectX 9.0c versions are unsupported on Windows 10, at least for me it popped an error, and those seem to come up very easily when searching for DirectX 9.0c, this information didn't solve the problem for me, put it pointed me to the right direction so credits to him, I guess. :3
Thanks for reading and have fun with Skyrim on Windows 10! :3